Liquid level responsive hydrodynamic flow control



Aplll 26, W, A SCHUL-rz f LIQUID LEVEL RESPONSIVE HYDRODYNAMIC FLOWCONTROL Filed Oct. 25, 1946 u um.Il

III

Inventor: Wi ibur Achulbz,

by ZM 7- fl/L .His4 Attorney:

' Panarea Apr. ze, 1949 LIQUID LEVEL RESPONSIVE HYDE@- VDYNAMIC FLOWCONTROL Wilbur A. Schultz, Lakewood, Ohio, assignor` to General ElectricCompany, a corporation of New 'Zork Application @ctober 25, i946, SerialNo. 795,536

I3 Claims.

The invention relates to automatic liquid level v control and providesimproved hydrodynamic now control mechanism suitable for oil burner orother pumping control services where a predetermined liquid level is tobe maintained.

The liquid level in any ilow lchamber or reservoir either rises or fallswhen the inlet flow rate exceeds or falls below the outlet ow rate.Ordlnarily some suitable form of automatic iloat operated flow controlmechanism is provided for controlling either the inlet or outlet flowrate to .maintain the desired liquid level. y

The principal object of the present invention is to provide a iloatlessform of liquid level responsive control by locating the inlet ofanimproved hydrodynamically operated flow control vmechanism at thedesired liquid level so as to selectively control in response t'o theilow oi either liquid or gas through said inlet.

Another object is to provide a vcomplementary flow rate control whereinone variable liquid iiow rate is dependent upon a secondary variableliquid or gas ilow rate and said secondary ilow rate in turnv isdetermined selectively by the level of the liquid flowing at said onevariable rate.

Another object is to provide a main flow rate control hydrodynamicmechanism having a secondary iiow inlet located at a predetermined levelfor the main liquid ilow and capable of inversely varying the main ilowrate dependent upon whether the liquid rises above or falls below thesecondary flow inlet.

Another oblect is to provide a main pump for pumping liquid into acontainer with control means including auxiliary 'pumping means havingan inlet eiective when the liquid level rises above a predeterminedlevel in the container for thereupon pumping the liquid to hydrodynamicmeans for decreasing the output of the main pump and vice versa.

Another object `is to combine the main pump with a coaxial jointlyoperable augiliary pump and associated hydrostatic control mechanism forvarying the rate f the main pump selectively dependent upon whether theauxiliary pump is pumping a liquid or a gas.

A further object is to provide a rotary blade main pump-with anauxiliary -pumping inlet and associated hydrodynamic pumping ratecontrol mechanism such asto enable the rotary blade pump toautomatically maintain a predetermined liquid level.

Further objects and advantages of the invention will appear in thefollowing description of the accompanying' drawings 'in 'which Fig. 1 isa CL. S-40) sectional view of an electric driven oil burner pumpingmechanism provided with the improved [liquid level responsivehydrodynamic pumping control of the present invention. Fig. 2 is a sec-5 tional view of the rotary blade pump mechanism shown in Fig. 1 lookingin the direction oi the arrows 2--2; Fig. 3 is a sectional view of thepumping mechanism provided with a modified form of liquid levelresponsive hydrodynamic control of the present invention; Fig. 4 is asectional view of the pumping mechanism shown in Fig. 3 looking in thedirection of arrows --l; Fig. 5 is a partial sectional view of theshielded auxiliary pump 'inlet structure of Fig. 1 showing more clearlythe details of construction; and Fig. 6 illustrates schematically arefrigerant pumping system embodying the invention.

Referring to Fig. 1, the rotary piston pumping mechanism indicatedgenerally by the reference character Ill-is of the type adapted tosupply oil and air under pressure to an oil burner atomizing nozzle asmore fully described and claimed in the Lum Patent 2,032,291.

Only a portion of the electric motor for driving the combined oil andair pumping mechanism IU is illustrated in Fig. 1, namely the electricmotoi` stator coils II, the motor rotor I2 mounted on shaft I3, thatcarries the main pump rotor I4, eccentrically within the cylinder bodyI5 between the upper end plate I6 and the lower end plate I l. p

As shown in Fig. 2 the pump rotor I4 is provided with the opposed slots20 carrying the cylinder sealing bladesl 2| therein. As more fullydescribed.

in the above mentioned Lum patent the upper and lower end plates I6 andI 1 are provided with suitable oil and air inlet and outlet passagescommunicating with the space inside of the cylinder body I5 so that bothoil and air are pumped under pressure into the pressure sump orreservoir 22 to be supplied therefrom to an atomizing burner dnozzle notshown. l

As shown in Fig. 1 the oil inlet passage 23 is formed in the upper endplate I6 with the port 24 located adjacent the path of oil inlet groove25 formed radially in the top face of the pump rotor I4 so as to connectthe oil inlet passage 23 with ,the vacuum space behind the blades 2I aslong as each of the grooves 25 registers with the port 24.

Thus upon rotation of the rotor I4 in a counterclockwise direction asindicated by the arrow in Fig. 2 the pump Ill exerts a suction on theoil inlet passage 23 so as to pump oil from a main storage .f reservoir(not shown) into the pressure sump 22.

Likewise, air is pumped .from the air inlet surge chamber 26 shown inFig. 2 through the lateral air v 3 inlet port 21 into the space behindthe blades 2l and both oil and air under pressure are discharged fromthe pump cylinder through the outlet passage 28 into the sump 22.

In order to maintain a predetermined oil level insidel the sump 22, theby-pass valve 30 is provided for controlling the suction on the oilinlet passage 23 so as to thereby vary the oil pumping rate. In carryingthe present invention in effect as shown in Fig. 1 the oil by-pass valve30 is operated by an improved hydrodynamic mechanism indicated generallyby the reference character :L

In the form shown in Fig. l, the valve 30 is operated by a piston 32that is biased by spring 33 to move upwardly inside the cylinder 34 toclose valve 38 on its seat 35. The space in cylinder 34 above piston 32communicates through passage 31 with an auxiliary pump 38 that iscoaxial with the main pump rotor I4 and is jointly operated by the pumpdriving rotor I2. As

shown in Figs. 1 and 2 the 'auxiliary pump cylinder 38 is formed in thelower end plate I 1 and provided with a pair of opposing sealing 'blades39 for supplying liquid under pressure through passage 31 to operatepiston 32 against the bias of spring 33. The inlet 40 into the auxiliarypump cylinder 38 is loc-ated at the predetermined level of the liquid tobe maintained in sump 22 upon operation of the main pump rotor I4. Asmore clearly shown in Fig. 5 in order to shield the auxiliary pump inlet40 from the foam or froth 4I which may be carried in the surface of theoil in the sump 22, the bame 42 is provided so that oil unmixed with airis supplied from the bottom of .the sump 22 to Ithe auxiliary pump inlet40.

Operation of Fig. 1

When the oil pumping mechanism I is started into operation uponenergization of the motor stator windings II, motor rotor lI2 drivesboth the main pump rotor I4 and the auxiliary pump rotor 38a. However,the auxiliary pump 38 is relatively ineffective as long as air is beingpumped through the inlet 40. Hence there is not suiiicient air pressureproduced to operate piston 32, since the air quickly leaks around theloose tting stem of valve 3u and thus bleedsaway the pressure frompiston 32. Consequently valve 30 remains closed. Thus the rotation ofthe main pump rotor I4 produces a relatively strong Y suction that drawsoil through the oil inlet passage 23 into cylinder I5. The oil alongwith air under pressure is discharged into the sump 22. But when the oilin sump 22 rises above the level of the auxiliary pump inlet 40, then anincreasing amount of oil is pumped by the auxiliary pump 38 throughpassage 31 to operate piston 32 against the bias of spring 33 andthereby open the by-pass valve 30 even though some of the oil bleedsaround the stem of valve 30. In case the oil level still continues torise then piston 32 will move downwardly until the increased volume ofoil pumped by the auxiliary pump discharges through the outlet passage44. .As soon asvalve 30 opens oil is supplied from sump 22 through thevalve port 35 to the oil inlet passage 23 since theoil in sump 22 ismaintained under a substantial pressure. Asa result, oil drawn from themain reservoir (not shown) is reduced in quantity and the oil level insum-p 22 will fall until just enough oil is being pumped by theauxiliary pump 38 to balance the bleed loss around valve stem 30 andthus maintain the valve 30 open suiiiciently to hold a predetermined oillevel in sump 22 as determined lby the location of the inlet port 48 ofthe auxiliary pump. Then in case the oil level in sump 22 fallsslightly, the bleed loss will exceed the auxiliary oil pumping rate andthe valve 30 will tend lto close and thus increase the pumping rate ofthe main pump I4 to supply more oil to the sump 22. On the other hand,when the oil level rises slightly in sump 22, more oil will be pumped bythe auxiliary pump 38 than is bled away so as to move piston 32 andincrease the opening of valve 30 ythereby regulating the suction of themain pump I4 so as to decrease the oil pumping rate thereof. When theoil level in sump 22 falls below the auxiliary pump inlet 40, then theauxiliary pump 38 can only pump air and due to thesubstantial clearancesaround the stem of valve 30. the air pressure'leaks away so that piston32 is not operated against the bi-as of spring Y33. Hence valve 30 willclose and remain closed until the oil level in sump 22 again rises up tothe pump inlet 40.

While pipe has been shown exten-ding into the oll'at the bottom of sump22, it will be understood that this pipe may -be eliminated if desiredand air supplied from the top of the sump 22 through valve port 35 so asto break or decrease the vacuum exerted on the oil inlet passage 23 andthereby decrease the main oil pumping rate. Otherwise the operation issubstantially the same.

In the modified form of hydrodynamic liquid level pumping control shownin Fig. 3, the main pump rotor I4 is able to perform lthe auxiliaryliquid level responsive lpumping function in addition to its normalfunction of pumping oil and air into the sump 22. This may beaccomplished as shown in Figs. 3 and 4 by providing the port in lthelower end plate Il with this port 50 communicating through passage 5Iwith the liquid level responsive inlet 40 located at the predeterminedoil level that is to be maintanied inside of sump 22. The arrangement issuch that port 50 communicates with each slot 52 formed in the bottomface of the main pump rotor I4 immediately after the slot 25 formed inthe upper face breaks communication with oil inlet port 24. In this waythe passage 5I is brought into communication with the suction space backof each blade 2l as long as slot 52 commnunicates with port 50, thuscreating a pumping suction on passage 5I. Preferably the slots 25 and 52in the opposite end faces of rotor I4 are .aligned directly oppositeeach other and the ports 24 and 50 are angularly displaced as indicatedin Fig. 4. However, to more clearly disclose the port constructiondetails Fig. 3 is somewhat distorted in indicating ports 24 and 50 as inthe same crosssectional plane. However, if such aligned portconstruction is desired then the slots 25 and 52 may be angularlydisplaced to produce the sequential communication with the correspondingports as outlined above The pressure responsive bellows 54 is providedfor operating the by-pass valve 30 and is normally biased by spring 54ato close valve 30 on its -port 35. The bellows 54 is carried by thethreaded mounting member 55 and the threaded plug 5B is provided forclosing oil* the interior of 'bellows 54 so that the inside of bellows55 may be subject by means of the Passage 45'! to the`4 suction existingin passage 5 I Operation of Fig. 3

cated. When the oil rises to the level oi the inlet lli, theni thesuction in the passage M is increased suillciently to cause bellows 54to collapse sufciently to open valve 3l. As a result oil passesfromsumpn through pipe Il directly into the oil inlet 2,3 and in thisway the oil level in sump 22 is prevented from rising above the inletI0. When the oil level falls below inlet Il, then the suction in passage5I decreases and bellows u will return valve 3|! to the closed positionthereby increasing the suction in the oil inlet passage n andcorrespondingly increasing the supply of oil to the sump 22. When theoil level partially covers the port l0, then a variable mixture oi airand oil will be pumped through passage il thereby creating a variablesuction on bellows d to variably open valve 30. In this way, the oilpumping rate into sump 22 may be modulated so as to maintain the oillevel in the sump substantially constant even though the outlet ilowrate to the burner atomizing nozzle may be varied considerably.

As previously indicated, pipe 65 may be omitted and air admitted byvalve 30 to partially break the vacuum of the oil inlet 23 if desired.Thus it will be seen that by .means of the present invention, the iioatfor operating the pumping rate control valve mechanism can be eliminatedandthe pumping rate controlled by a more reliable and eiiicienthydrodynamic mechanism either of the piston type as shown in Fig. l orof the bellows type as shown in Fig. 3.

In the refrigerant pumping system shown in Fig. 6, the compresser E0 isconnected to pump gas from the evaporator 6I and supply the compressedg-as through conduit 62 to the condenser 63. The liquiiied refrigerantdrains from condenser 63 through conduit 64 into the liquid reservoir55. The valve 66 is provided for regulating the flow of liquidrefrigerant from reservoir 65 through conduit 'H into the evaporator Si.

In order to operate valve 66 so as to maintain a predetermined liquidlevel in reservoir 65 in accordance with the present invention, thebellows 61 is operatively connected with valve 66 and provided with thespring 68 for biasing valve I8 to the closed position. The bellows 61 isinterconnected by means of the conduit 69 with the outlet conduit 1I andthe bellows 61 is provided with a ow metering oriilce 1li located at thedesired liquid level inside of the reservoir 65.

. ,s substantially at the predetermined level at which metering oriilce1li is located.

What I claim as new and desired to secure by Letters Patent oi theUnited States is:

1. A liquid level'- control system having in combination means includinga movable element for regulating the liquid level, iluid now producingmeans having a ow passage provided with an inlet opening at apredetermined desired level for the liquid, and means dependent upon theadmission of gas and liquid to said passage for selectively operatingsaid element when the liquid s rises above and falls belowsaid inletopening.

2. A liquid level control system having in combination plural means forproducing flow, one having a ilow inlet for providing a flow ratedependent upon variations in the level of the liquid ow produced by theother, and means responsive to the flow rate of said one means forregulating the liquid now rate of said other means selectively tocounteract said variations.

3. In combination, a container for liquid, means including a valve forregulating the liquid level in said container, fluid flow producingmeans having a dow passage provided with an inlet opening at apredetermined desired level for the liquid, and pressure responsivemeans responsive to the pressure variations produced upon admission ofgas and liquid to said passage for reversely operating said valve whenthe liquid rises above and falls below said inlet opening.

4. In combination, a container for liquid having means including a valvefor regulating the Y liquid level therein, iluid iiow producing meanshaving a flow passage with a flow inlet opening at a predetermined levelinside said container and means responsive selectively to the admissionof gas and liquid to said` passage for reversely operating said valve tomaintain the liquid in said container substantially at saidpredetermined level.

5. In combination acontainer for liquid. means including a pressureresponsive device and a ow regulating valve actuated by said device forvary- Preferably conduit 69 oil'ers resistance to huid ow substantiallyequal to the resistance oilered by metering orifice 10.

Operation of Fig. 6

Upon operation of the compressor I0 suction is applied to the evaporator6I and thence ing the liquid level'in said container, and suction meansinterconnected with said device and having an inlet disposed at apredetermined level in said container for reversely varying the pressureof said pressure responsive device when the liquid rises above and fallsbelow said inlet.

6. In combination, a container having liquid supply means including apump, means including a valve for controlling the operation of said pumpto vary the liquid level in said container, and means including asuction inlet for said pump disposed at a predetermined level in saidcontainer and pressure responsive means responsive to the pressurevariation produced upon admission of gas and liquid into said inlet forreversely operating said valve.

7. In combination a pump having a pressure responsive by-pass valve for-varying the pumping rate thereof, and means including an auxil- "iarypump having an inlet disposed at a predeliquid reaches the flow meteringorifice 10, then sufiicient reduction of pressure inside of bellows 61is obtained to contract the bellows il and thereby open valve 66. Uponthe resulting decrease in liquid level 'within the reservoir I5. thenthe pressure inside bellows 61 will again increase toclose valve 66. Inthis way valve 66 is positioned by the operation of bellows 6l so as tomaintain the liquid level inside of reservoir l5 termined liquid levelfor supplying liquid under pressure to operate said by-.pass valve whenthe liquid rises above said level.

8. In combination a rotary blade pump having`- a by-pass valve forvarying the liquid pumping rate thereof. a pressure responsive deviceoperav tively connected with said va1ve,'and means .including anauxiliary rotary blade pump coaxial with said main pump and driventhereby and having an inlet located at a predetermined liquid level forvarying the pressure of said device to 5 operate said valve to reverselyvary the pumping in said sump.

amai-1s nation, a pressure sump having pumping. meansfor supplying oiland air under pressure thereto, and hydrodynamic means including asuction inlet .for said pumping means located in said container at apredetermined oil level ,and a pr essure responsive by-pass valveresponsive 4difierentlaliy to air and oil flow through said inlet forregulating the oil pumping rate of said pumping means to maintain saidpredetermined oil level 10. An oil burner mechanism having in combination a pressure sump, va rotary pump provided with one inlet forpumping oil and another inlet for pumping air under pressure into saidsump, said pump having a third inlet communicating with said sump at apredetermined level for the oil therein, and means including a pressureresponsive by-pass valve responsive differentially to air and oil flowthrough said third inlet for regulating the suction at said one oilinlet to maintain said predetermined oil level in said sump.

11. A liquid level control mechanism having in combination a containerfor retaining a body of liquid at a predetermined desired level, meanshaving an inlet opening at said level for withdrawing iluid from saidcontainer, control means responsive differentially to the admission ofgaseous and liquid fluid to said opening, means having an inlet belowsaid level for withdrawing liquid from said body, and ow regulatingmeans controlled by said control means for increasing the rate of ilowof liquid through said liquid withdrawing means upon the admission ofliquid to y said rst-mentioned inlet opening 'and for decreasing therate of flow upon the admission of gaseous fluid to said iirst opening.A

1 12. In combination, a fluid container, means including a pump forsupplying iluid under pressure to said container, means including avalve for admitting to said pump iluid from said container, means forcontrolling said valve to maintain a predetermined desired liquid levelin said container, said control means comprising a pumping devicehavingan inlet opening in said container at said desired level and beingarranged to open and close said valve upon the admission of liquid andgaseous iluid respectively to said inlet opening.

13. In combination, a fluid container, means including a pump forsupplying iiuid under pressure to said container, means including avalve for-admitting to said pump iiuid from said container, means forcontrolling said valve to maintain a predetermined desired liquid levelin aid container, said Vcontrol means having an i let opening at saidliquid level for withdrawing liquid and gaseous iluid from saidcontainer and being responsive differentially to the admission ofgaseous and liquid fluid to said opening to operate said valve and toreversely vary the pumping rate of said pump when the liquid rises aboveand falls below said inlet opening.

- WILBUR A. SCHULTZ.

REFERENCES CITED The following references are of record in the file oithis patent:

UNITED'STATES PATENTS Number Name Date 683,630 Westinghouse Oct. 1, 1901688,286 Blevney Dec. 10, 1901 1,530,066 Wood Mar. 17, 1925 1,914,541Teesdake June 20, 1933

